1. Field of the Invention
This invention relates generally to mattresses and mattress overlays and more particularly to an apparatus and method for making a segmented or multi-sectioned mattress or overlay using a honeycomb core.
2. Description of the Prior Art
Foam and gel-filled materials have long been used in mattresses and cushions to absorb shock and provide support for various parts of the human body. More recently, honeycomb cores have been used to provide improved support characteristics for such applications. However, either the inherent characteristics of these materials or the methods used to form the pads have resulted in less than optimum configurations for applications in which the pads must be folded, must have different support characteristics across their surface, or are intended to accommodate multiple users.
For the case in which the mattress must be folded either in use or for storage, unless the pad is segmented and seamed together, its thickness prevents folding and it usually must be rolled. On the other hand if the pad is segmented to accommodate storage, the junctions of the segments present seams or spaces that interfere with uniform support during use.
For example, some mattresses and seat cushions include one or more sections of foam material encased within a covering, with the foam being configured and formed to provide comfortable supporting surfaces. Where multiple foam cushions are combined in a single unit, the unit must rely on the integrity of the casing to hold the cushions in their intended relative positions. This usually requires that the cushions be placed in individual pockets separated by a seam of some type that normally makes it difficult to prevent unwanted separations between adjacent cushion parts. If a plastic casing is used, the separation problem is usually worse due to the type of bonding seam that is normally used. There are also other shortcomings associated with the use of foam materials. For example, foam is susceptible to taking a compression set after many periods of use wherein the foam cells collapse and the support benefit of the cushion is lost.
In other prior art mattresses and cushions, a gel or other fluid-like substance is used to fill an impermeable sack which is disposed within or on a foam envelope. The entire assembly is encased within a moisture resistant cloth, vinyl and/or urethane, or waterproof covering and placed on a seat or mattress support. In some cases the gel-filled cushion is formed with contours or contact-free zones to relieve contact and pressure on sensitive portions of the user's body. U.S. Pat. No. 5,201,780 (Dinsmoor, III et al.) discloses a tri-layered mattress pad that includes a cover or casing containing an interior strata of a plastic film layer atop a fluid bladder layer supported on a foam layer. This pad cannot be folded due to its complicated internal construction.
Other prior art mattresses that include a matrix of air or fluid cells that may be inflated and deflated to more evenly support body parts, although flexible enough to be bent or folded, usually include complicated plumbing components and in addition to the fluid supply components (e.g. compressor, valving, tubing, etc.), a computer is often needed to constantly measure and control the reaction of each air cell to pressure and load changes by varying the deflation and inflation in each cell. Thus, such mattresses are also costly and complicated.
Honeycomb structures are now often selected as the preferred padding for use in mattresses and other cushions intended to support a human body. For example, Landi et al U.S. Pat. No. 5,701,621 disclose various improved mattress and mattress pad configurations made from one or more layers of single panel, flexible elastomeric honeycomb core encased within a covering fabricated from a porous or fabric material. The honeycomb core in one disclosed embodiment is faced on the bottom side with a plastic facing sheet having a plurality of perforations to permit expulsion of moisture from the core. In another embodiment, the mattress pad includes facing sheets attached to both the upper and lower surfaces of a single core. A covering encases both the core and facing sheets. The honeycomb core of this embodiment may include cell walls having perforations formed therein so that each cell of the core can communicate with a pumping subsystem to allow control of the firmness of the pad.
Another Landi et al embodiment includes two honeycomb core panels disposed one atop the other with both cores being encased within a single covering that may be permeable or may be constructed with side openings or vents that are impervious to gas and fluids. The cell walls of each core may be solid, i.e. non-perforated, or some or all of the cell walls of the cores may include a plurality of perforations. In still another embodiment, a dual core pad having three facing sheets is disclosed wherein each facing sheet is solid, i.e. non-perforated, or may be formed with a plurality of perforations. The facing sheets are respectively bonded to the upper surface of the upper core, the lower surface of the upper core and the adjacent upper surface of the lower core, and the bottom surface of the lower core. The facing sheets may be solid, i.e. non-perforated or may be formed with a plurality of perforations.
Although providing substantial improvement over the previous materials, each of these honeycomb embodiments is constructed of single core layers and is thus not ideally suited for applications in which folding is required, in which substantial non-planer orientation or support is contemplated, in which support of more than one human body is intended to be accommodated, or in which different anatomical support characteristics are to be had in different areas of a single mattress or mattress overlay.
There thus remains a need to provide a method of making an improved mattress or mattress overlay that overcomes the above stated deficiencies and maximizes comfort, durability, shape maintainability, storability and utility, yet does not possess the shortcomings of the prior art.